Formic Acid → 5-bromo-4-methoxy-1H-benzimidazole

Temperature

100 °C

A 1 L four-necked round bottom flask fitted with a magnetic stirrer was dried and cooled under a stream of nitrogen then charged with 4-bromo-3-methoxy-benzene-1,2-diamine (61 g, 0.28 mol, 1.0 equiv.) in formic acid (200 mL). The reaction mixture was heated at 100° C. for 2 h, cooled and quenched with ice water (1 L). The reaction mixture was basified with 10% NaOH solution and extracted with ethyl acetate (2×1000 mL). The separated organic layers were combined, washed with brine solution (750 mL), dried (Na2SO4), filtered and concentrated in vacuo. The crude material was purified by SiO2 chromatography eluting with an EtOAc/hexane gradient (30-50% EtOAc) to afford 6-bromo-7-methoxy-1H-benzoimidazole (36 g, crude) as a brown solid. 1H NMR (300 MHz, DMSO-d6): δ 4.26 (br, 3H), 7.16 (s, 1H), 7.29-7.32 (d, 1H), 8.19 (s, 1H), 12.67 (br, 1H).

1. customA 1 L four-necked round bottom flask fitted with a magnetic stirrer
2. customwas dried
3. temperaturecooled under a stream of nitrogen
4. temperaturecooled
5. customquenched with ice water (1 L)
6. extractionextracted with ethyl acetate (2×1000 mL)
7. washwashed with brine solution (750 mL)
8. dry with materialdried (Na2SO4)
9. filtrationfiltered
10. concentrationconcentrated in vacuo
11. customThe crude material was purified by SiO2 chromatography
12. washeluting with an EtOAc/hexane gradient (30-50% EtOAc)

ORD record

ord-629ba2a9d8574fedacd79be42d543631

Source dataset

uspto-grants-2014_01

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US08637537B2